Comment by belzebalex

Built one of the first 3d ultrasonic scanner that works in the air to make an autonomous drone [1] [2]

[1]: https://www.alextoussaint.com/2021-04-28_How-I-built-an-ultr...

[2]: https://hackaday.com/2021/05/15/a-phased-array-ultrasonic-3d...